Heat pump water heaters provide an energy and cost-efficient way to heat water with electricity. These types of heaters typically provide the same amount of hot water as electric resistance water heaters, but do so at about one-half to one-third the energy cost. Heat pump water heaters may also have the added benefit of providing air-conditioning as a by-product of water heating.
Heat pump water heaters work by transferring heat, not by generating heat. Typically, a heat pump water heater uses a standard vapor refrigeration compression cycle in reverse. In this manner, a heat pump water heater uses a closed-loop heat exchange circuit to absorb heat from a source (such as air in a room) and transfers the heat to a heat sink (such as water in a water storage tank). The energy consumed in a heat pump water heater system is the energy to run a compressor to circulate the refrigerant in the heat exchange circuit.
One drawback to heat pump water heaters is their installation costs. Because heat pump water heaters include the piping and ventilation of air and water, installation costs can be more expensive than conventional water heaters. Moreover, the components of the heat pump water heaters add to the cost of manufacturing the device because heat pump water heaters typically require more parts than a standard water heater or heat pump.
What is needed therefore is a heat pump water heater design and construction that maintains the benefits of a heat pump water heater but decreases the manufacturing and installation costs.